But that's not very interesting. It all depends on what you want to do with it. A server and a desktop system have very different requirements. Same goes for a desktop system with Xorg and a lightweight WM and software collection (or maybe even without Xorg and just console applications) versus Xorg and one of those big DEs.

I recommend you play with the BSDs and determine which ones meet your needs with your small memory sizes. Use virtual machines to determine what your application set requires, and what is possible.

The monolithic OpenBSD/i386 kernel (uniprocessor or multiprocessor) is 8.5MB. So 8MB would be too small. I have not run a 16MB Intel based machine in some years, but I would suppose that 16MB could be a possible minimum.

Note that for OpenBSD, Intel 386 CPU support was dropped some years ago. The oldest technology supported is Intel 486 and its clones.

Don't use the memory requirements outlined in my OpenBSD live media FAQ -- that memory requirement is significant due to memory based filesystems. (link in my .sig.)

For NetBSD, have a look at one of the INSTALL.* files under the architecture of your choice. E.g., for i386 INSTALL.html says

Quote:

NetBSD 5.1.1_PATCH runs on all i486 or later PC-compatible systems with 1 to 32 processors. The minimal configuration for a full, standard installation is 32MB of RAM and 250MB of disk space.

Note that support for actual 80386 cpu was put into mothballs some time ago, whereby it would only continue if somebody stepped up to keep it going. Seems like no-one has, not surprizingly. (The above link may become invalid at any time.)

Ooh, IdOp, I hadn't considered looking in the INSTALL.* files for OpenBSD. According to INSTALL.i386, 40386 or better processors and 24 or 32MB of RAM and 200MB of disk are the minimal configurations.

Of course, the older architectures have lower minimums. For example, the mvme68k architecture (Motorola 680x0 VME) minimum is 12MB of RAM and 160MB of disk. For Vax, the lowest amount of tested memory is 8M.

I want the computer to behave as a file server, mail server (for now only fetchmail or equivalent) and also to wget or curl some files for me and to feed some of the text from those files to a rss/atom service (that I still have to find out how).
I asked for the default memory footprint, because the memory requisites for these services don't seem to be great.